Iran is an arid country with ristric water resources. Due to water shortage and waste water pollution, waste water treatment is very important case in this cuntry. Today, several methods such as airobic, anairobic and chemical treatment were uses for wastewater treatment. This studty was conducted for investigating the ability of four adsorbents of activated carbon, natural zeolite, peat and biochar for waste water treatment of a potato processing plant in batch and column condition. Study results showed that all adsorbents could reduce COD, but the best resuls accured by activated carbon. Langmuier and Frendlich isoterm models had the best corolation with study results and Pseudo-second-order model predicted the kinetics of adsorption process very well. This study confimed that natural zeolite as a natural adsorbent is a good choice for COD reduction as compared to activated carbon. Keywords: Activated carbon, Clinoptilolite zeolite, Adsorption capacity, Pseudo-second-order model, Freundlich model.
